AIMS_BD_IATI.WebAPI.Controllers.IATIImportController.SubmitHierarchy C# (CSharp) Method

        public FilterBDModel SubmitHierarchy(HeirarchyModel heirarchyModel)
        {
            if (Sessions.activitiesContainer.IsHierarchyLoaded == true)
                return null;

            var returnResult = new FilterBDModel();
            heirarchyModel = heirarchyModel ?? Sessions.heirarchyModel;

            var iatiActivities = Sessions.activitiesContainer?.iatiActivities;
            if (heirarchyModel == null)
            {
                returnResult.iatiActivities = ToMinifiedIatiActivitiesModel(Sessions.activitiesContainer?.iatiActivities);
            }
            else
            {

                if (heirarchyModel.SelectedHierarchy == 1)
                {
                    iatiActivities = ImportLogic.LoadH1ActivitiesWithChild(iatiActivities);
                    returnResult.iatiActivities = ToMinifiedIatiActivitiesModel(iatiActivities, false, true);
                }
                else
                {
                    iatiActivities = ImportLogic.LoadH2ActivitiesWithParent(iatiActivities);
                    returnResult.iatiActivities = ToMinifiedIatiActivitiesModel(iatiActivities);
                }
                Sessions.activitiesContainer.IsHierarchyLoaded = true;
            }
            returnResult.iatiActivities = returnResult.iatiActivities.OrderByDescending(k => k.IsRelevant).ToList();

            Sessions.CurrentStage = Stage.FilterBD;
            Sessions.heirarchyModel = heirarchyModel;
            Sessions.filterBDModel = returnResult;
            Sessions.activitiesContainer.iatiActivities = iatiActivities;
            return returnResult;
        }